Droplet sizing by Mie scattering interferometry in a spark ignition engine

A theoretical explanation is given of a technique based on Mie scattering i nterferometry (MSI)I obtained by defocusing of the collecting optics, to si ze droplets. The originality of this study is the development of a droplet sizing method by planar laser light scattering for the case of a scattering angle range close to 90 degrees. The feasibility of this method and its li mitations are fully described. The dependence on intensity levels and refra ctive index variations can be neglected. After discussion of some practical details about particle size, imaging and camera constraints, the results o btained in the combustion chamber of a spark ignition (SI) engine, near the spark plug, prior to ignition and for different injection timings an descr ibed and discussed. It can be concluded that the implementation of the MSI method in this exper imental set-up has been realized successfully to provide droplet distributi ons in an SI engine. To allow the easier use of the technique, image proces sing software will be developed in the Matlab environment.